The invention relates to an apparatus for the injection molding of plastic materials, wherein the closing force which acts on the divided mold is transmitted by two plates through which pass beam members which are supported against the outsides of the plates.
The plates against which the beam members are supported by way of nuts, pressure pads or the like bend typically under the influence of the closing force applied, in particular when the mold is substantially smaller than those plates. As a result the nuts assume an inclined position and the beam members which are in any case heavily loaded in tension by the closing force are subjected to flexural loadings in their end region. That limits the service life of the beam members.
The invention is based on the consideration that the beam members which are subjected to a loading should be kept as free as possible from flexural forces, which in accordance with the invention is achieved in that the support for the beam members is effected by means of a pressure-loaded support device which in the loaded condition, on the side of the beam members which is towards the edge of the plate, is of a greater extent in the beam member direction than on the side which is towards the center of the plate.
There are various options in regard to structurally carrying the concept of the invention into effect. In particular the nuts, pressure pads or the like which enlarge the ends of the beam members are supported by way of sleeves against the plate which is bent by the closing force, in which case on the side towards the edge of the plate the sleeves are of the greatest wall thickness or the greatest height.